Is Your Project Timeline Based on a Sample of 1? Do this INSTEAD...

Let’s face it, as human beings we’re terrible at estimating how long a project will take to complete (even Elon Musk has been off by YEARS in his predictions for SpaceX!)

𝗪𝗛𝗬? Two reasons:

❌ We’re simply too optimistic and assume everything will go well.

❌ Calculating a single completion time does not FORCE us to consider alternate scenarios.

Once the date been communicated, everyone tends to remember THE DATE – and not the underlying assumptions behind it - no matter how carefully they're stated.

𝗔 𝗦𝗼𝗹𝘂𝘁𝗶𝗼𝗻?

A variation of PERT analysis; PERT stands for 𝘗𝘳𝘰𝘨𝘳𝘢𝘮 𝘌𝘷𝘢𝘭𝘶𝘢𝘵𝘪𝘰𝘯 𝘢𝘯𝘥 𝘙𝘦𝘷𝘪𝘦𝘸 𝘛𝘦𝘤𝘩𝘯𝘪𝘲𝘶𝘦. Even though it was first used by the US Navy in the 50’s for the development of the Polaris submarine-launched nuclear missile, it’s not rocket science:

In PERT, for each project task we calculate 3 durations:

👉 Optimistic (O): min. time to accomplish (best-case scenario)

👉 Pessimistic (P): max. time to accomplish (worse-case scenario)

👉 Most Likely (M): best current estimate to accomplish

A project plan for each of the three scenarios can then be developed and analyzed in MS Project, Excel, etc. to determine a RANGE of project durations and completion dates.

𝐁𝐄𝐍𝐄𝐅𝐈𝐓𝐒 𝐨𝐟 𝐏𝐄𝐑𝐓 𝐢𝐧𝐜𝐥𝐮𝐝𝐞:

✅ A series of realistic scenarios for our project based on what can go right AND what can go WRONG!

✅ NOT being tied down to a single (uncertain) date, since the output is a RANGE of completion times.

✅ An estimate of the VARIABILITY in our project timeline.

Even IF a completion date cannot be moved (say due to an audit or regulatory deadline), the three estimates can be used to calculate project duration with:

🔹 Additional resources (Optimistic)

🔹 Current resources (Most Likely)

🔹 Less resources (Pessimistic)

Which can help us figure out whether we’ll need additional people, machines, material, etc. to meet our deadline.

We would not make an important decision based on a sample of n = 1 if we could avoid it, so why base your project timeline on a single estimate?

Give PERT analysis a try when scheduling your next project.